It is commonplace in the motor vehicle industry for the vehicle to have a wheel and hub assembly having a wheel hub and a spindle. In traditional wheel hub assemblies, the road engaging wheel/tire is connected to a spindle assembly that is rotatably mounted in a stationary hub portion that is connected to the vehicle. The spindle is rotatably mounted on bearings interposed between the stationary hub and the rotating spindle. In front wheel drive hub/spindle assemblies, the spindle is operatively connected to and driven by an axle of the motor vehicle.
Tapered bearings have been found to be particularly advantageous for use in such assemblies. The tapered bearings are coaxially mounted within the stationary hub or carrier portion of the assembly, about the axis of the axle. Tapered bearings must have proper specified load or pre-load pressure applied to them in order to operate efficiently and for obtaining maximum life. In the past, pre-load pressure has been applied to the bearings from the inboard side of the spindle assembly by means of a lock ring applied to the spindle shaft by a press-fit technique. The lock ring adheres to the outer spindle surface by the frictional interface engagement between the lock ring and the spindle as the lock ring slides along the spindle. As the lock ring slides along the spindle shaft, it slidably engages and applies pressure to the tapered bearing assembly. With such systems, it is extremely difficult to accurately axially position the lock ring relative to the spindle so as to apply precise pre-load pressure to the tapered bearings. It can be appreciated that due to the method of assembling the lock ring to the spindle, pressure to the lock ring can only be applied in one direction. Accordingly, it is extremely difficult to accurately position the lock ring relative to the shaft and the tapered bearings so as to apply the optimum pre-load pressure to the tapered bearings. Application of too much pressure to the bearings can result in premature bearing failure; whereas not enough pressure will result in a loose hub/spindle assembly which will also cause premature failure. Therefore, there is a significant need for a hub/spindle assembly and apparatus which allows optimum pre-load pressure to be applied to the tapered bearing assembly.
The press-fit lock ring hub/spindle structure of the prior art is also not user friendly from a manufacturing viewpoint. It is typical for such press-fit lock rings to be applied by impact tools over which the assembler has little application pressure control. Further, once the press-fit lock ring assembly is applied to the spindle, it is very difficult to later change the ring position or to remove it in the event of a subsequent repair operation.
As a result of the foregoing issues with hub/spindle assemblies incorporating tapered bearings, a number of hub/spindle manufacturers have entirely eliminated the tapered bearings from such assemblies in favor of less efficient cylindrical ballbearing assemblies which do not require accurate pre-load pressure to be applied to the bearing assembly. A disadvantage of the use of such cylindrical ballbearing assemblies is that their incorporation into the spindle assembly typically requires the thickness of the hub or bearing carrier portion of the assembly to be thinned down in order to accept the cylindrical bearing. Others have resorted to heat treating both the bearing carrier and spindle assemblies and actually using them as a raceway for ballbearings inserted therebetween, such that the entire hub and spindle assembly itself acts as a bearing.
The present invention addresses the needs and shortcomings of prior hub/spindle assemblies for driven spindle configurations. The invention provides a simple, reliable and cost-effective approach for assembling the hub/spindle assembly in a manner that incorporates the advantages of using tapered bearings therewith, and for accurately and precisely applying pre-load pressure to the bearings so as to obtain maximum performance and life therefrom. The invention also provides for an accurate and reliable seal configuration for maintaining the lubrication within the hub/spindle assembly.